Back wired electrical receptacle having spring contacts for gripping conductors



July 3. 1956 EI R. CARLSON 2753,533

BACK wIRED ELECTRICAL RECEPTACLE HAVING SPRING CONTACTS FOR GRIFPINC CoNnUCIoRs Filed May 26. 1954 INVENTOR ATTQRNEYS.

Unite States Patent O BACK WIRED ELECTRICAL RECEPTACLE HAV- ING SPRING CONTACTS FOR GRIPPING CON- DUCTRS Ernest R. Carlson, Fairfield, Conn., assignor to Harvey Hubbell, Incorporated, Bridgeport, Colm., a corporation of Connecticut Application May 26, 1954, Serial No. 432,342

Claims. (Cl. 339-164) This invention relates to an electrical receptacle having means whereby one or more attachment plug caps may be plugged into the receptacle for supplying electrical current to various devices or attachments, and has for an object to provide an improved and simplified construction whereby lead wires for supplying current to the receptacle may be connected to the receptacle contacts without the use of binding screws and by merely inserting the stripped or bared ends of the lead wires into openings in the back of the body of the receptacle.

It is another object to provide means whereby the leads so inserted are firmly and effectively gripped by means associated with the electrical contacts to hold them against withdrawal from the receptacle, and also which are so arranged that the greater the pull on the leads to withdraw them from the receptacle the greater is the gripping action on these leads.

A further object is to provide a new construction and arrangement with readily operable and effective means for quickly and easily releasing the gripping means securing these lead wires, so that they may be readily withdrawn and disconnected from the receptacle if desired.

Another object is to provide an improved means for gripping the blade contacts of attachment plug caps plugged into the receptacle to hold these blades against accidental withdrawal under normal operation, and also to provide a better and more effective electrical contact between the receptacle contacts and the blade contacts of the cap.

lt is still another object to provide an improved con struction in which the receptacle contacts are arranged in laterally spaced pairs in which each of the plurality of contacts and conductor members are of the same construction and the same form, and the contact members of each pair are arranged in reversed relation to cooperate with each other in gripping and holding the lead wires from the house wiring or other supply system and also to grip and hold the contact blades of attachment plug caps plugged into the receptacle.

Still another object is to provide a construction of this type in which each of the contact and conductor members in the receptacle are of the same size, form and construction so that they may all be blanked and formed from the same dies.

With the foregoing and other objects in View, I have devised the construction illustrated in the accompanying drawing forming a part of this specification. It is, however, to be understood the invention is not limited to the specific details of construction and arrangement shown, but may embody various changes and modifications Within the scope of the invention.

In this drawing:

Fig. 1 is a front view of a duplex outlet receptacle embodying this invention, and which is adapted for mounting in suitable wall outlet boxes and similar electrical installations;

Fig. 2 is a rear View of the receptacle;

Fig. 3 is a front view of the back member of the body Patented duly 3, 1955 with the front member removed and showing the receptacle contacts in place, and showing in section a pair of contact blades of an attachment plug cap inserted between the receptacle contacts;

Fig. 4 is a transverse section on the plane of line 4-4 of Figs. 3 and 5;

Fig. 5 is a longitudinal section substantially on line 5-5 of Fig. 3, but showing the front member in place;

Fig. 6 is a similar longitudinal section substantially on line 6-6 of Fig. 3;

Fig. 7 is a transverse section substantially on line 7 7 of Figs. 3 and 5, and

Fig. 8 is a perspective View of one of the contact members removed.

As previously indicated, the device shown comprises a duplex outlet receptacle adapted for mounting in a standard Wall outlet box or similar device of a house wiring system, for plugging in the standard attachment plug caps for supplying current to various electrical devices or attachments. It comprises an insulating body 10 formed of two members, a rear or back member 11 and a front member 12, and these members may be molded from any suitable insulating material, such, for example as Bakelite or other similar plastics. Within the body are mounted a plurality of receptacles and contacts, and they comprise two laterally spaced pairs of contact members 13. Each of these members comprises a strip of metal formed substantially as shown in Figs. 3 and 8, and the four members are of the same construction and form and the two members of each pair are arranged side by side, as shown in Fig. 3, and in reversed relation so that the two members of each pair cooperate to grip and hold a lead Wire inserted into the receptacle from the rear side thereof for connection to the house wiring system, and also form spring grips for gripping and holding the contact blades of a standard attachment plug cap plugged into the receptacle for supplying current to various electrical de vices, as will presently be described.

The back or rear member 11 of the body is provided with a pair of laterally spaced central chambers 14 in the central portion of the body and at each of the opposite ends with a pair of laterally spaced. end chambers 15, these chambers being separated by transverse dividing walls or lugs 16 and 17 having a slot or opening 18 between them. At the outer or opposite ends of the chambers 15 the body is provided with a cross wall 19 provided with an open-sided recess 20 communica-ting with each chamber 15. The chambers 15 at each end of the body are separated by a longitudinal rib or wall 21, and the chambers 14 are separated by a similar rib or wall 22 having a central boss 23 and two longitudinally spaced bosses 24 at its opposite ends adjacent the lugs 16.

The contact members 13 as indicated comprise resilient metal strips forming electrical conductors and contact members. It includes a central portion 25 having at its opposite ends transversely extending beads 26 and transversely extending offset portions 27 separating the central portion 25 from the opposite end portions 28. The end portions 28 form receptacle contacts and are substantially flat, except at their top edges they have a laterally bent or inclined rib 29 separated from the offset 27 and liat free end portions 30 by notches or recesses 31. One of the Contact portions 28 is alsol provided with a laterally pressed bump or lug 32 a short distance in wardly of the inclined rib 29. The central portion 25 is also provided with a longitudinal bead 33 pressed into the strip, and when the contacts are assembled in the back member 11 of the body these beads are on the inside opposed to each other. The intermediate portions 25 are inclined to each other in opposite directions, as indicated in Fig. 4, with the inner edges 34 opposite to the back wall 35 of the body member nearer together than the opposite edges 34a of these members at the inner side of the back wall, and this back wall 35 is provided with openings 36 leading to these inclined central portions 25 of the Contact strips, as shown in Figs. 3 and 4, for insertion of the stripped ends 37 of one or more lead wires 38 connected with the house wiring system and terminating in the wall outlet or similar box (not shown) in which this receptacle is mounted. These intermediate portions 25 of the contact members are therefore inclined inwardly toward each other toward their edges 34 from the openings 36, or are inclined outwardly away from each other from their inner edges 34 toward these openings.

As previously indicated and as shown in Fig. 3, the two pairs of contact members 13 are mounted in the back member 11 of the body in the laterally spaced position, and the contact members of each pair are placed side by side in reversed relation. This places the central portions 25 and the beads 26 rwithin the chambers 14, with the beads 26 at the inner side of the lugs 16 and 17, the oifset portions 27 seated side by side in the slots or recesses 18 between the lugs 16 and 17, and the contact portions 28 in the chambers 15 with their free end portions 3t) in the recesses 20 in the end walls 19. The slots or recesses 18 are only of suicient width to provide clearance for easy insertion of the offset portions 27 side by side in mounting the contacts in the member 11, the beads 26 acting as locating stops cooperating with the lugs 16 and 17 to properly position the contacts longitudinally in the body member and prevent them from shifting longitudinally out of position. The recesses 20, however, in which the free ends 30 of the Contact members are located, are wider than the thickness of these members to permit limited separation of the free ends, but will prevent separation beyond a given amount, for a reason presently to be described.

The front member 12 of the body covers the open forward side of the back member 11 after contact members 13 have been mounted in this back member, and they are held together by a pair of drive screws 39 inserted through openings in the back member 11 located in the bosses 24 and driven into sockets 40 in the front member 12, as shown in Fig. 6. This front member therefore retains the contact members 13 in their positions in the back member 11. This front member also has a pair of longitudinally spaced thickened portions or bosses 41 each provided with a pair of laterally spaced inlet slots 42 leading to the chambers 15 and in alignment with the contact portions 23 of the contact members 13 and the laterally bent guiding ribs 29. These slots are for insertion of the contact blades 43 of the conventional or standard attachment plug caps connected by suitable conducting wires with any suitable type of electrical device or attachment. A pair of these blades are shown inserted between the contacts 2S at the right hand side of the receptacle in Fig. 3, and as the laterally inclined ribs 29 are in alignment with the inlet openings 42 and are inclined outwardly in opposite directions on the two contact members 28, they will act as guides to guide the blades 43 to a position between the two contacts 28. The ribs 29 will also act as camming means to force the contacts 23 apart as the blades 43 are inserted between them. The recess in which the outer free ends 30 of the contacts are located is wide enough to permit a certain amount of separation of these end portions when the blade 43 is inserted between the two contacts, but will not permit as great separation as the thickness of the blade 43, and therefore further spreading of the portions 23 carrying the ribs 29 by the blade 43 puts these contacts under tension for a spring clamping action on the blade 43, giving a greater holding effect and also a better electrical contact between the contacts 28 and the blade 43. Also when the blade is in this position the bump or lug 32 on the receptacle contact enters the opening 44 in the blade to provide a still further gripping means to resist withdrawal of the blade from the receptacle.

It will also be seen from Figs. 3 and 4 that as the stripped end 37 of the lead wire 38 is inserted through an opening 36 in the back wall 35 to a position between the inclined intermediate portions 25 of the contact members it will spread apart the inner edges 34 of these members as they are normally spaced less than the thickness of the wire 37, and this spreading apart of the portions 25 will place them under tension so that there is a spring action pressing these edges 34 against the opposite sides of the wire 37. This will cause the inner corners of these edges which are relatively sharp to tend to bite into the opposite sides of the wire somewhat and to hold the wire against withdrawal from the receptacle, and because of the inclined arrangement of the portions 25 and the backing up of the outer edges 34a by the rear wall 35, the greater the pull on the wire tending to withdraw it from the receptacle the greater will be the tendency for these inner edges 34 to bite into the wire and to increase its grip on the wire. This will not only provide a good iirm grip on the wire but it will also provide the required effective electrical contact between the wire and the Contact members 13.

In the arrangement shown there are two openings 36 shown in alignment with the central portions 25 of each pair of contacts. This will permit insertion of the lead wires at a choice of diierent positions, and also if the openings are made of different sizes they could be used for different gauges or sizes of lead wires. The inner wall of the outer member 12 is provided with sockets 45 in alignment with the openings 36 to receive the free ends of the inserted wires 37 and assist the openings 36 in retaining these wires in proper position between the contact members 25.

Means is also provided for separating the inclined portions 25 to release their grip on the lead wires and permit withdrawal of the lead wires from the receptacle if desired. For this purpose the back wall 35 is provided with an elongated slot 46 in alignment with the inclined portions 25 of the pair of contact members, and located between the openings 36 for insertion of the lead wires. The slots are also in alignment with the beads 33 on the contact members, which, as previously indicated, are on the inner sides of these members, as shown in Fig. 7. These slots permit the insertion of the bit of a screw driver or similar element, as indicated in broken lines 47 of Fig. 7, between these beads and force the inclined portions 25 apart to free the gripping edges 34 from the wire 37 and thus release the wire and permit it to be withdrawn from the receptacle. If the bit is not of suicient thickness to spread the edges enough to release the wire, the bit may be turned somewhat and cause a camming action on the beads 33 to separate the contacts and release the wire.

A metal bridge is also provided for mounting this receptacle in a wall outlet box (not shown). This bridge is indicated at 48 and is provided with ears 49 at its opposite ends for mounting in the wall box by any suitable means, such, for example, as screws in the slots 50. The bridge has a narrow intermediate portion 51 extending between and connecting these end portions, and seated in suitable longitudinal grooves or channels 52 in the inner surface of the front member 12 of the body, as it is thus between the two opposed faces of the two members 11 and 12 it is retained in this groove or channel by the rear member. The central portion 53 is exposed in an opening 54 in the center of the front member 12 between the bosses 41 and is provided with a tapped opening 55 to receive the securing screw for any suitable type of face plate (not shown) for covering the open side of the wall outlet box after the receptacle has been mounted therein. The back member 11 may be provided with a socket 56 in alignment with this opening closed or sealed olf at the bottom by the rear wall to receive and cover the inner end of this screw.

It will be seen from the above that this provides a simple, effective construction of an outlet receptacle in which no binding screws are required for securing the lead wires to the receptacle contacts, eliminating the time and difficulty in securing these wires by these binding screws, and also eliminating the possibility of the screws becoming loose and permitting the released wires to form short circuits. It will also be apparent that the lead wires may be connected easily and quickly by merely inserting the stripped ends of the lead wire into one of the openings 36 for receiving it in the rear Wall of the receptacle, and that although a firm grip is automatically provided on this Wire, still it may be easily and quickly released by a screw driver or similar instrument, and that the four contacts are all of the same construction and form and therefore may be blanked and formed from a single set of dies. Still further, that the arrangement and means for mounting these contacts provide a firm spring grip of the receptacle contacts on the inserted contact blades of the plugged-in attachment plug cap, reducing to a minimum the liability of accidental separation of the cap from the receptacle and providing an effective electrical contact between the receptacle contacts and the blade contacts.

Having thus set forth the nature of my invention, I claim: l

l. In an electric receptacle an insulating body, two laterally spaced pairs of contact member mounted in said body, the contacts of each pair being of the same construction and located side by side in reversed relation and including receptacle contacts adjacent their ends, said body provided with inlet slots in its front Wall for insertion of the contact blades of an attachment plug cap between the receptacle contacts of each pair for engagement therewith, said body being also provided with openings in its back wall for insertion of lead wires to positions between the members of each pair, and said members having portions inclined laterally in opposite directions away from their edges opposite said openings providing gripping edges to grip the lead wires and hold them against withdrawal from the body.

2. In an electric receptacle an insulating body, contact members mounted in said body comprising a pair of metal strips of the same construction arranged side by side in reversed relation extending longitudinally of the body and including receptacle contacts adjacent their ends, said body provided with inlet slots in its front wall for insertion of the contact blades of an attachment plug cap between said receptacle contacts for engagement therewith, said body being also provided with an opening in its back wall for insertion of a lead wire to a position between said strips, and said strips having portions in alignment with said opening inclined laterally toward each other from the opening providing edges on their opposite sides from the opening to grip the wire and hold it against withdrawal from the body and forming guides to direct the wire to a position between said edges.

3. In an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, said strips each having receptacle contacts adjacent its opposite ends and an intermediate portion between said contacts inclined to the plane of the contacts so that the inner edges of the inclined portions are closer together than their outer edges adjacent the back wall of the body, said back Wall provided with an opening for insertion of the stripped end of a lead wire to a position between said inclined portions and between the inner edges thereof to be gripped thereby, and the front wall of the body provided with slots in alignment with the receptacle contacts for insertion of the blade contacts of an attachment plug cap to a position between adjacent receptacle contacts to be gripped thereby.

4. In an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, said members including receptacle contacts at the opposite ends of said members, said strips including intermediate portions between said contacts laterally inclined in opposite directions so that their inner edges are closer together than their outer edges adjacent the back wall of the body, said back wall provided with an opening for the insertion of the stripped end of a lead wire to a position between said inclined portions and between the inner edges thereof to be gripped thereby, and the front wall of the body provided with slots in alignment with the receptacle contacts for insertion of the blade contacts of an attachment plug cap to engage the receptacle contacts.

5. ln an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, said strips having receptacle contacts side by side adjacent their opposite ends and free end portions in recesses at the ends of the body, said strips including intermediate portions between said contacts laterally inclined in opposite directions so that their inner edges are closer together than their outer edges adjacent the back wall of the body, said back wall provided. with an opening for the insertion of the stripped end of a lead wire to a position between said inclined portions and between the inner edges thereof to be gripped thereby, the front wall of the body provided with inlet slots in alignment with the receptacle contacts for insertion of the blade contacts of an attachment plug cap to a position between adjacent contacts to be gripped thereby, said receptacle contacts being normally closely adjacent so as to he separated by insertion of the blade contacts, and said recesses being of a width to limit separation of the free ends of said strips by the blade contacts so that the strips are bent and placed under spring tension by insertion of the blade contacts.

6. In an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, said strips having receptacle contacts side by side adjacent their opposite ends and free end portions in recesses at the ends of the body, means for connecting a lead wire to the contact members between the receptacle contacts, the front wall of the body provided with inlet slots in alignment with the receptacle contacts for insertion of the blade contacts of an attachment plug cap to a position between adjacent contacts to be gripped thereby, said receptacle contacts being normally closely adjacent so as to be separated by insertion of the blade contacts, and said recesses being of a width to limit: separation of the free ends of said strips by the blade contacts so that the strips are bent and placed under spring tension by insertion oi the blade contacts.

7. ln an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, said strips having receptacle contacts side by side adjacent their opposite ends and free end portions in recesses at the ends of the body, the front wall of the body provided with inlet slots leading to the receptacle contacts for insertion of the blade contacts of an attachment plug cap to a position between adjacent contacts to be gripped thereby, said receptacle contacts being normally closely adjacent and provided with laterally inclined ribs at their outer edges having a camming action with the blade contacts to separate the receptacle contacts as they are inserted between them, said recesses being of a width to limit separation of the free ends of the strips by the blade contacts so that the strips are bent and placed under spring tension by insertion of the blade con- 7 tacts, and means for connecting a lead wire to the contact members between the receptacle contacts.

8. In an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, receptacle contacts at the opposite ends of said members, said strips including intermediate portions between said contacts laterally inclined in opposite directions so that their inner edges are closer together than their outer edges adjacent the back wall of the body, said back wall provided with an opening for the insertion of the 'ripped end of a lead wire to a position between said inclined portions and between the inner edges thereof to be gripped thereby, said back wali also provided with an opening to one side of the rst opening for insertion of an implement between said inclined portions and by camming action of its side walls to separate the inner edges thereof to release the lead wire, and the front wall of the body provided with slots leading to the receptacle contacts for insertion o the blade contacts of an attachment plug cap to engage the receptacle contacts.

9. In an electric receptacle an insulating body, contact members in said body comprising a pair of metal strips extending longitudinally of the body and placed side by side, receptacle contacts at the opposite ends of said members, said strips including intermediate portions between said contacts laterally inclined in opposite directions so that their inner edges are closer together than their outer edges adjacent the back wall of the body, said back wall provided with an opening for the insertion of the stripped end of a lead wire to a position between said inclined portions and between the inner edges thereof to be gripped thereby, said inclined portions being each provided with a longitudinal bead on the side adjacent the other member, said back wall also provided with an opening for insertion of an implement between said beads and by camming action thereon to separate the inner edges of said inclined portions and release the lead wire, and the front wall of the body provided with slots leading to the receptacle contacts for insertion of the blade contacts of an attachment plug cap to engage the receptacle contacts.

l0. In an electric receptacle an insulating body including a member provided with a pair of laterally spaced chambers at each of its opposite ends and a pair of laterally spaced intermediate chambers located one between the corresponding chambers of the two end pairs and separated from each of the adjacent end chambers by a transverse wall provided with an open sided transverse recess through it, two pairs of laterally spaced contact members, each pair comprising two conductor strips placed side by side, said strips of each pair comprising receptacle contacts in the aligned end chambers and intermediate portions in the intermediate chamber between these end chambers, said contact members of each pair also including opposed oiset portions between the intermediate portions and the receptacle contacts seated in said recesses in the separating walls between the chambers to position the contact members, means for connecting lead wires to the intermediate portions of the contact members, and said body provided with inlet slots in its front wall leading to the end chambers for insertion of the contact blades of attachment plug caps to engage the receptacle contacts.

References Cited in the tile of this patent UNITED STATES PATENTS 1,839,522 Alden Ian. 5, 1932 1,950,826 Smart Mar. 13, 1934 2,671,204 Hubbell Mar. 2, 1954 OTHER REFERENCES Publication, Electrical Construction and Maintenance, August 1953, page 52 and 53. 

